6-Aryl-3[2H]pyridazinones, as starting materials or intermediates for the synthesis of pharmaceuticals and plant protection agents, and a process for their preparation are described, for example, by Baddar et al. (J. Chem. Soc. 1965, 3342), Steck [J. Heterocycl. Chem. 11 (1974) 755], Albright et al. [J. Heterocycl. Chem. 15 (1978) 625], Pitarch et al. [Eur. J. Med. Chem-Chimica Therapeutica 9 (1974) 644] and Curran et al. [J. Med. Chem. 17 (1974) 273] or are known, inter alia, from the following descriptions: German Offenlegungsschrift Nos. 2,435,244, 2,445,681 and 2,757,923.
6-aryl-3[2H]pyridazinones are also known from, for example, the following descriptions: German Offenlegungsschrift Nos. 2,427,943, 2,810,267, 2,845,220, European Offenlegungsschrift Nos. 8,391, 10,156, Japanese Preliminary Published Application No. 58,008,105 and U.S. Pat. No. 4,397,854.